Dual goals of trunk restriction and stability are prioritized by individuals with chronic low back pain during a volitional movement.
Stephanie L Jones, Juvena R Hitt, Sharon M Henry
PMID 34358848WHAT IT FOUND
People with active low back pain stood up by restricting trunk movement and using more knee and ankle motion.
Despite this 'knee strategy', they maintained stability similar to healthy controls by generating greater braking forces with their leg muscles.
Key findings
01Participants with low back pain demonstrated restricted trunk movement and increased knee torque compared to healthy controls.
02Despite using a knee-dominant strategy, participants with low back pain achieved similar center of mass stability to healthy controls.
03Stability was maintained through increased activation of distal muscles (tibialis anterior, hamstrings, rectus femoris) and greater braking forces.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
Small sample size (13 per group). Participants had chronic, recurrent pain but were tested during an acute flare-up (average pain 3/10), so results may not apply to those in severe pain or pain-free periods. Fear of movement was not measured, so the study cannot confirm whether the trunk restriction was driven by pain-related fear or passive tissue stiffness. The study used a laboratory setting with specific chair height and arm-crossed constraints, which may not reflect real-world transfers.
Declared interests
The authors have no conflicts of interest. The study was supported by the NIH (Extramural).
The easy way to misread this
Do not interpret the restricted trunk movement and high knee torque as signs of instability or poor motor control. The study found that these patients maintained center of mass stability comparable to healthy controls, suggesting this pattern is a successful compensatory strategy to protect the spine.